Cis- and Trans-Regulatory Mechanisms of Gene Expression in the ASJ Sensory Neuron of Caenorhabditis elegans

Abstract

The identity of a given cell type is determined by the expression of a set of genes sharing common cis-regulatory motifs and being regulated by shared transcription factors. Here, we identify cis and trans regulatory elements that drive gene expression in the bilateral sensory neuron ASJ, located in the head of the nematode Caenorhabditis elegans. For this purpose, we have dissected the promoters of the only two genes so far reported to be exclusively expressed in ASJ, trx-1 and ssu-1. We hereby identify the ASJ motif, a functional cis-regulatory bipartite promoter region composed of two individual 6 bp elements separated by a 3 bp linker. The first element is a 6 bp CG-rich sequence that presumably binds the Sp family member zinc-finger transcription factor SPTF-1. Interestingly, within the C. elegans nervous system SPTF-1 is also found to be expressed only in ASJ neurons where it regulates expression of other genes in these neurons and ASJ cell fate. The second element of the bipartite motif is a 6 bp AT-rich sequence that is predicted to potentially bind a transcription factor of the homeobox family. Together, our findings identify a specific promoter signature and SPTF-1 as a transcription factor that functions as a terminal selector gene to regulate gene expression in C. elegans ASJ sensory neurons.

The glutathione system and the related thiol network in Caenorhabditis elegans

“…The trx-1 gene is specifically expressed in the ASJ neurons [ 143 ]. Discovery of an ASJ motif, a functional cis -regulatory promoter region, has been reported to regulate the ASJ-specific gene expression of trx- 1 by binding SPTF-1, an ortholog to the Sp family zinc-finger transcription factor [ 144 ]. Mutant worms that lack the trx-1 gene are more vulnerable to paraquat-induced oxidative stress [ 145 ] and have decreased lifespans [ 143 , 145 ].…”

Expression of thioredoxin‐1 in the ASJ neuron corresponds with and enhances intrinsic regenerative capacity under lesion conditioning in C. elegans

“…These effects can be mitigated by pursuing a reverse genetic screen under ribonucleic acid interference (RNAi) to test genes that have an expected role in conditioned regeneration. A similar screen was successfully carried out on transcription factors regulating non‐conditioned trx‐1 expression [54].…”

Expression of thioredoxin-1 in the ASJ neuron corresponds with and enhances intrinsic regenerative capacity under lesion conditioning inC. elegans

“…-16-regeneration. A similar screen was successfully carried out on transcription factors regulating non-conditioned trx-1 expression (Gonzalez- Barrios, et al, 2015).…”

“…These effects can be mitigated by pursuing a reverse genetic screen under RNAi to test genes that have an expected role in conditioned DRAFT regeneration. A similar screen was successfully carried out on transcription factors regulating non-conditioned trx-1 expression (Gonzalez- Barrios, et al, 2015).…”